2020

Water Labs and the Drinking Water Sector: Two Peas in a Pod

To be able to 'read' the water quality of the Meuse, water laboratories and drinking water companies are increasingly joining forces. This is essential, as the need for information is growing steadily. To meet this rising demand, water labs are constantly tweaking their analytical methods. The symbiosis between the labs and the drinking water sector is leading to accelerated innovation—with the icing on the cake being progressive insight into the water quality of the Meuse. How does this work in practice? Gerdien de Kloe from Aqualab Zuid explains the world of drinking water analysis.

More Focus on Substances

Research into chemical substances is not new, but the technical possibilities are now greater than ever. Due to new developments in analytical chemistry, particularly in mass spectrometry, far more substances can be detected simultaneously. In addition, scientific research is also focusing on effect-directed monitoring. Thanks to automated, cell-based assays, it is now possible to quickly create risk profiles for many new substances at the same time.

As a result, more and more knowledge is within reach, especially regarding new substances. The more substances you measure, the more you know. This offers opportunities for the drinking water sector. However, it also creates dilemmas: what should you focus on in the monitoring program? It is precisely for this reason that drinking water companies are working more intensively with water laboratories. What developments are they dealing with?

Trends

De Kloe: "To begin with, interest in traditional, existing analyses is declining. That is perfectly fine, because if you have analyzed a set of components for 10 years and barely ever find them, it is better to shift your focus to new, relevant substances." The question is: which ones?

"We are seeing an increasing demand for the analysis of highly polar substances—components that dissolve well in water and are highly mobile. Such substances are difficult to remove during water treatment, meaning there is a high probability they will end up in drinking water. This demand for insight into highly polar substances is growing, partly due to the PFAS environmental disaster. To measure these substances, we as a lab are pushing the boundaries of what is technologically possible." More on that later.

De Kloe also notes another relevant trend: as of 2020, a vast amount of information is being shared within the sector. "The great thing is that if a water laboratory or Rijkswaterstaat (the Directorate-General for Public Works and Water Management) measures a certain component, other drinking water companies immediately want to know more about it too. Furthermore, not only is more information being requested, but it all has to happen faster. For example, just this week we dealt with a discharge into the Rhine of an industrial substance of very high concern. When a substance from the 'ZZS list' (Substances of Very High Concern) is detected, all the alarm bells ring, and action must be taken swiftly."

Innovation for Accurate Detection

Because the industry never stands still and constantly develops new substances, the laboratory must search for analytical methods that can get the job done. This involves both new screening methods and improved detection techniques. In other words: it is about overview and accuracy. The driving force behind this innovation is the fact that more and more substances in the Meuse turn out to be relevant (toxic) even in extremely low concentrations. High-tech solutions are required to bring information about these new substances to light.

To give an example: in 2020, Aqualab acquired a Triple Quad Mass Spec System (for target compound analysis) to determine known substances with high accuracy. "It is currently one of the most sensitive devices on the market. Next year, we might have to purchase an additional machine. That is how fast the demand for analyses is growing."

Broad Screening and QTOF

According to De Kloe, it is not just about innovation for the more accurate detection of known target substances in low concentrations, but also about new techniques for broad screening. "A broad screening provides information on the occurrence of new substances (peaks). As soon as you know a substance is permanently in the picture, you want to be able to determine it accurately. This requires a solid target compound method. In short: target analysis follows screening, but there needs to be a good synergy between the two methods."

De Kloe points to screening with the QTOF, which stands for quadrupole time-of-flight (QTOF) mass spectrometry (MS). "This allows us to detect pharmaceuticals, pesticides, and drugs. We work with a substance library of over 2,000 known substances. In addition, we use the QTOF to screen for industrial substances that we currently have little visibility on. This category includes substances that were previously responsible for major incidents on the Meuse, such as pyrazole (2016), melamine (2018), and PFAS (2020)."

Measurement Method for Highly Polar Substances

"During screening, special attention is paid to polar substances. We measure a broad set, but technically we still struggle with the analysis of highly polar substances. It turns out that different separation methods are required for them."

With this goal in mind, the KWR research institute developed the 'multimode method' two years ago, based on advanced chromatography. "By using different types of separation methods, or chromatography columns, you can look at different sets of (polar) substances. In other words: after an improved separation of components, the detection of highly polar substances also becomes more feasible. We are going to adopt this method in-house. However, we also want to use this method for new screening purposes, to see what other unknown polar substances are present in the Meuse water."

De Kloe expects this improved separation and screening to yield a lot of new information. "Many industrial substances are metabolized in the treatment plant, making them more polar. Consequently, these metabolites become so mobile that they pass through the treatment process and end up in the Meuse. That is vital information for drinking water companies; they want to get a clear picture of it."

Successful Identification

The optimization of analytical methods is already bearing fruit. A few years ago, researchers at Aqualab Zuid managed to identify 8-HPA (8-hydroxypenillic acid). "The drinking water companies had been troubled by these substances in the Meuse for more than a year and a half. Drinking water company WML had to repeatedly halt its water intake because of it. Following our identification of the components, WML took immediate action toward the discharger. The discharge stopped immediately. This demonstrates the importance of identifying new substances. Drinking water companies can target the problem directly with the discharger, and the industry can then look for solutions."

A walk in the park? Not exactly, because for many substances, measurement efforts do not immediately result in environmental gains. This applies to PFAS, for example. "PFAS substances are toxicologically highly relevant. Health-based guideline values are becoming very low, down to concentrations in the order of nanograms per liter. The point is that PFAS substances are actually being detected in these concentrations, both in surface water and in drinking water. Because they can no longer be removed from the water, we have to prepare ourselves for the fact that we will likely still have PFAS substances in the environment for the next 20 years.

An additional challenge is that with these low standards, we are right on the edge of what is technically feasible to measure. As a result, we have to deal with a large margin of error in the measurement results. In short: while we can measure more and more, it doesn't mean the problems have vanished. PFAS is a complex problem that the drinking water sector will continue to face in the coming years."

Evaluation of Substances Relevant to Drinking Water

What lies ahead? Which substances should drinking water companies target in the coming years? This question forms the core of the 'evaluation of drinking water-relevant substances' being prepared by the water labs on behalf of the drinking water sector.

De Kloe: "We are currently mapping out new substances, using both literature and our own measurement data. Next, we assess the toxicological relevance of candidate substances. After being tested against specific criteria, the substances are deemed 'drinking water-relevant' or not. If they receive the 'drinking water-relevant' stamp, it means they will be monitored for at least three years."

An evaluation is being carried out to determine for sure whether the current 36 drinking water-relevant substances still belong in the regular monitoring program (and thus need to keep being measured as target compounds). This means the current list of 36 drinking water-relevant substances is being re-evaluated.

What happens next? It appears to be a matter of work in progress. "Based on the initial literature review, we have compiled a list of 100 potentially new substances. If it turns out they are not toxicologically relevant, they will disappear from the list. The final results of the evaluation will be incorporated into next year's monitoring program."